Perseus Double Cluster

[RobertM]

Taken from home in sunny Orpington on 27/11.



Link to full size: http://farm8.staticflickr.com/7032/6447177773_81cfd1940a_o.jpg

Capture Details:
HyperStar C11 (570mm f/l) + SX M25C, 62 x 120s

TFL
Robert

[MarkS]

Very nice!

I love the star colours and the collimation appears to be spot on.  To be very picky, you do have an almost imperceptible but pretty uniform elongation in the Dec direction across the whole frame.  Is that a guiding issue?

Mark

[The Thing]

Lovely Robert. Ignore Mark, he is sooo picky.

[Fay]

I leave the very technical problems to the clever ones!!!! I think it is very nice, visually pleasing, nice change to see a couple of clusters

[JohnP]

Looks good Robert - Also agree with Mark very minor star elongation.

Also remnants of a satellite trail top to bottom to left of left hand cluster (dark blue colour)

Robert - I stretched your image in PS - moved the grey (middle pointer) in levels - looks like whole area is swathed in dust - also have some weird looking dark lanes (especially to bottom) - don't know if that's real or remnant of processing..

Very nice though - John

[RobertM]

God, you people are so picky but yes I was aware of those issues too.

John, those imperfections in the background, at least one of which I believe, is down to the flats calibration (which I intend to redo at some point).  The trouble is that it's difficult pinpointing exactly what is real image and what is an optical imperfection and there don't seem to be any really deep images to compare with.  The streak along the bottom is a something I need to look into as I'm not quite sure where it's coming from yet.  I'll process once I've sorted out those issues.

Mark/John, the guiding was good so the elongation is a bit of a mystery.  One possible explanation is that the camera cables (which are quite thick) are causing it - look at the direction of the spikes - they are all aligned exactly the same way as the elongation.  As you say it could still be the guiding and I'll double check that when I'm next out but I'm a bit sceptical as it only seems to be affecting those stars with spikes.  I'll reorient the cables to see if that makes a difference.

Many thanks for the feedback
Robert

[JohnP]

God, you people are so picky 

Robert - only being Picky because the image is so bloody good & I'm jealous..... 

There is definitely loads of dust (nebula around it) - look at this old APOD:

http://apod.nasa.gov/apod/image/0901/clusters_2_ritter.jpg

I reckon if you sort out your backgrounds you should reprocess with the background higher - you have definitely captured it al.. Star colours great as well...

[RobertM]

Thanks for the kind comments John.  It's very reassuring to know that not all the strange gradients are defects..

That's a very nice APOD that !

[Mac]

Nice capture.

That's a very nice APOD that !

Are you sure its not fays? 

MAc.

[RobertM]

Nice capture.

That's a very nice APOD that !

Are you sure its not fays? 

MAc.

Difficult to tell 

[Fay]

You must all have such good eyes regarding issues, i cant see any of them. Time to put my binoculars on!

[Carole]

A beautiful image Robert, like Fay, I can't see any issues, except that the spikes seem to be leaning to the right, I have no idea what this means though. 

Carole

[MarkS]

One possible explanation is that the camera cables (which are quite thick) are causing it - look at the direction of the spikes - they are all aligned exactly the same way as the elongation. 

Agreed, the spikes and the elongation are in the same direction.  I should have spotted that!

[The Thing]

One possible explanation is that the camera cables (which are quite thick) are causing it - look at the direction of the spikes - they are all aligned exactly the same way as the elongation. 

On the basis that a curved spider vane creates self cancelling diffraction artifacts i.e. no spikes, could you put in a curved cable guide e.g. a bit of coat hanger wire, attach the cables and get rid of those pesky spikes? Not that I can see any spikes - must get an eye test soon!

[Fay]

well, now i blow it right up, i can see the leaning spikes, but would not have noticed them if it had not been mentioned.